Serial sectioning methods were used to study Ca self-diffusion in single crystals which contained up to 75ppm of cation impurities (table 182). The data for temperatures ranging from 987 to 1246C could be described by:

D (cm2/s) = 5.35 x 103 exp[-4.15(eV)/kT]

By analyzing the results on the basis of a Ca-ion vacancy diffusion mechanism, the migration enthalpy was estimated to be 1.75eV. The order of magnitude of the pre-exponential factor could be explained on the basis of lattice-strain entropy effects.

M.F.Berard: Journal of the American Ceramic Society, 1971, 54[3], 144-6

 

 

Table 182

Self-Diffusion of Ca in CaF2 Single Crystals

 

Temperature (C)

D (cm2/s)

987

1.15 x 10-13

987

1.18 x 10-13

1020

5.58 x 10-13

1020

4.10 x 10-13

1048

1.15 x 10-12

1063

1.16 x 10-12

1095

1.59 x 10-12

1116

5.42 x 10-12

1151

9.18 x 10-12

1182

1.15 x 10-11

1205

4.94 x 10-11

1205

5.10 x 10-11

1226

6.13 x 10-11

1246

1.18 x 10-10